text: /*
   * VC-1 and WMV3 parser
   * Copyright (c) 2006-2007 Konstantin Shishkov
   * Partly based on vc9.c (c) 2005 Anonymous, Alex Beregszaszi, Michael Niedermayer
   *
   * This file is part of Libav.
   *
   * Libav is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * Libav is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with Libav; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  /**
   * @file
   * VC-1 and WMV3 parser
   */
  
  #include "parser.h"
  #include "vc1.h"
  #include "get_bits.h"
  
  typedef struct {
      ParseContext pc;
      VC1Context v;
  } VC1ParseContext;
  
  static void vc1_extract_headers(AVCodecParserContext *s, AVCodecContext *avctx,
                                  const uint8_t *buf, int buf_size)
  {
      VC1ParseContext *vpc = s->priv_data;
      GetBitContext gb;
      const uint8_t *start, *end, *next;
      uint8_t *buf2 = av_mallocz(buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
  
      vpc->v.s.avctx = avctx;
      vpc->v.parse_only = 1;
      next = buf;
      s->repeat_pict = 0;
  
      for(start = buf, end = buf + buf_size; next < end; start = next){
          int buf2_size, size;
  
          next = find_next_marker(start + 4, end);
          size = next - start - 4;
          buf2_size = vc1_unescape_buffer(start + 4, size, buf2);
          init_get_bits(&gb, buf2, buf2_size * 8);
          if(size <= 0) continue;
          switch(AV_RB32(start)){
          case VC1_CODE_SEQHDR:
              vc1_decode_sequence_header(avctx, &vpc->v, &gb);
              break;
          case VC1_CODE_ENTRYPOINT:
              vc1_decode_entry_point(avctx, &vpc->v, &gb);
              break;
          case VC1_CODE_FRAME:
              if(vpc->v.profile < PROFILE_ADVANCED)
                  vc1_parse_frame_header    (&vpc->v, &gb);
              else
                  vc1_parse_frame_header_adv(&vpc->v, &gb);
  
              /* keep AV_PICTURE_TYPE_BI internal to VC1 */
              if (vpc->v.s.pict_type == AV_PICTURE_TYPE_BI)
                  s->pict_type = AV_PICTURE_TYPE_B;
              else
                  s->pict_type = vpc->v.s.pict_type;
  
              if (avctx->ticks_per_frame > 1){
                  // process pulldown flags
                  s->repeat_pict = 1;
                  // Pulldown flags are only valid when 'broadcast' has been set.
                  // So ticks_per_frame will be 2
                  if (vpc->v.rff){
                      // repeat field
                      s->repeat_pict = 2;
                  }else if (vpc->v.rptfrm){
                      // repeat frames
                      s->repeat_pict = vpc->v.rptfrm * 2 + 1;
                  }
              }
  
              break;
          }
      }
  
      av_free(buf2);
  }
  
  /**
   * Find the end of the current frame in the bitstream.
   * @return the position of the first byte of the next frame, or -1
   */
  static int vc1_find_frame_end(ParseContext *pc, const uint8_t *buf,
                                 int buf_size) {
      int pic_found, i;
      uint32_t state;
  
      pic_found= pc->frame_start_found;
      state= pc->state;
  
      i=0;
      if(!pic_found){
          for(i=0; i<buf_size; i++){
              state= (state<<8) | buf[i];
              if(state == VC1_CODE_FRAME || state == VC1_CODE_FIELD){
                  i++;
                  pic_found=1;
                  break;
              }
          }
      }
  
      if(pic_found){
          /* EOF considered as end of frame */
          if (buf_size == 0)
              return 0;
          for(; i<buf_size; i++){
              state= (state<<8) | buf[i];
              if(IS_MARKER(state) && state != VC1_CODE_FIELD && state != VC1_CODE_SLICE){
                  pc->frame_start_found=0;
                  pc->state=-1;
                  return i-3;
              }
          }
      }
      pc->frame_start_found= pic_found;
      pc->state= state;
      return END_NOT_FOUND;
  }
  
  static int vc1_parse(AVCodecParserContext *s,
                             AVCodecContext *avctx,
                             const uint8_t **poutbuf, int *poutbuf_size,
                             const uint8_t *buf, int buf_size)
  {
      VC1ParseContext *vpc = s->priv_data;
      int next;
  
      if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
          next= buf_size;
      }else{
          next= vc1_find_frame_end(&vpc->pc, buf, buf_size);
  
          if (ff_combine_frame(&vpc->pc, next, &buf, &buf_size) < 0) {
              *poutbuf = NULL;
              *poutbuf_size = 0;
              return buf_size;
          }
      }
  
      vc1_extract_headers(s, avctx, buf, buf_size);
  
      *poutbuf = buf;
      *poutbuf_size = buf_size;
      return next;
  }
  
  static int vc1_split(AVCodecContext *avctx,
                             const uint8_t *buf, int buf_size)
  {
      int i;
      uint32_t state= -1;
      int charged=0;
  
      for(i=0; i<buf_size; i++){
          state= (state<<8) | buf[i];
          if(IS_MARKER(state)){
              if(state == VC1_CODE_SEQHDR || state == VC1_CODE_ENTRYPOINT){
                  charged=1;
              }else if(charged){
                  return i-3;
              }
          }
      }
      return 0;
  }
  
  static int vc1_parse_init(AVCodecParserContext *s)
  {
      VC1ParseContext *vpc = s->priv_data;
      vpc->v.s.slice_context_count = 1;
      return ff_vc1_init_common(&vpc->v);
  }
  
  AVCodecParser ff_vc1_parser = {
      .codec_ids      = { CODEC_ID_VC1 },
      .priv_data_size = sizeof(VC1ParseContext),
      .parser_init    = vc1_parse_init,
      .parser_parse   = vc1_parse,
      .parser_close   = ff_parse1_close,
      .split          = vc1_split,
  };
  